Mounting roof rail with expansion bolt instead of bolt and nut

ravergarab

New member
Bora
You do not give the model of your sprinter but most have threaded holes. they are usually an M8 thread, I have had some heavy loads on those rails, the ambulances have all there flashy and noisy things held on those rails, no problems with a piece of canvas. Eric
How can I tell if mine are threaded without removing the plug? I'm stuck with the problem, I don't want to spend a full week removing the existing paneling, but I'd do if it I had no choice!
 

ravergarab

New member
It really depends, which type of roof rail are you wanting to attach?
I haven't bought anything yet, I'm still researching for now, I was really hoping the sockets would be threaded and use something like Loctite Threadlocker Red 271, to mount something like this one: https://www.sprinterstore.com/product/144-wheelbase-sprinter-van-roof-rack-track-kit/
The idea is to feel safe about installing solar panels + awning + skybox! Any suggestions are more than welcome, I think at this point I made peace with removing all the paneling!
 

OrioN

2008 2500 170" EXT
I haven't bought anything yet, I'm still researching for now, I was really hoping the sockets would be threaded and use something like Loctite Threadlocker Red 271, to mount something like this one: https://www.sprinterstore.com/product/144-wheelbase-sprinter-van-roof-rack-track-kit/
The idea is to feel safe about installing solar panels + awning + skybox! Any suggestions are more than welcome, I think at this point I made peace with removing all the paneling!
North American Sprinters do not have 'sockets'. There are only holes with plugs.
 

sparkplug

Well-known member
I think my comment about "Well Nuts" may have got lost in the thread.

While I wouldn't use them to support a whole lot of weight, they should be fine for a solar panel.

This is what they are:


Combine with some liberal application of Sika Flex around the hole (and some loctite if you want on the thread) they shouldn't be going anywhere or letting in any water.

They may need replacing every few years but they're inexpensive and easy to install so that's not an issue for me.
 

Eric Experience

Well-known member
Bora.
I have looked at my Ncv3 vans and they all have m8 captive nuts, so yours probably has. If not then you could fit a set, very easy to install, much better than the rubber units because you do not have to hold the nut while tightening and also you can remove the screw at any time without having to worry about the nut turning. That add shows imperial screws which are out dated, the world is metric with a much better range of fastenings than the old system. Eric.
 

borabora

Well-known member
Bora.
I have looked at my Ncv3 vans and they all have m8 captive nuts, so yours probably has. If not then you could fit a set, very easy to install, much better than the rubber units because you do not have to hold the nut while tightening and also you can remove the screw at any time without having to worry about the nut turning. That add shows imperial screws which are out dated, the world is metric with a much better range of fastenings than the old system. Eric.
As far as I know US Sprinters do not have captive nuts installed from the factory. My problem is that I don't have access to the inside/underside of the van because the previous owner has installed paneling that I want to keep.
 

Aqua Puttana

Poly - Thread Finder
Many fasteners can add up to strength.

How much strength is needed?

Enough for:
Uplift from wind at highway speeds.
Shear strength for stopping/crash.

Fasteners combined with good quality adhesive/VHB tape can be very strong.

:2cents: vic
 

borabora

Well-known member
Are the holes too big for Rivnuts?
I don't think rivnuts can deal with the metal sleeve that is welded to the bottom of the hole. I believe that rivnuts need to expand fairly close to the screw head but that's not the case because there's a sleeve to get through first. With a tight fitting bolt, I'd think epoxy would do the job but then you better love that rack because it's not coming down again. Maybe a long bolt with the head cut off and epoxied into the sleeve with a nut holding the rack might do the trick.
 

gltrimble

Well-known member
I don't think rivnuts can deal with the metal sleeve that is welded to the bottom of the hole. I believe that rivnuts need to expand fairly close to the screw head but that's not the case because there's a sleeve to get through first. With a tight fitting bolt, I'd think epoxy would do the job but then you better love that rack because it's not coming down again. Maybe a long bolt with the head cut off and epoxied into the sleeve with a nut holding the rack might do the trick.
Yes, the metal roof sleeve could present a problem with using Rivnuts. Although they are available with a grip range up to 0.5”. Probably not easy to find just the right size. Maybe some type of thread insert would work. Tap hole just enough for insert to engage should make for a strong connection. Spot welding some studs is even an option. Easy touch up with paint.
 

Eric Experience

Well-known member
Bora.
The inside of the metal sleeve has an M8 thread in it. you can make your life a lot better by leaning the metric system Eric
 

borabora

Well-known member
Bora.
The inside of the metal sleeve has an M8 thread in it. you can make your life a lot better by leaning the metric system Eric
I don't know where you are located but I have seen pictures of US NCV3s and the sleeve was definitely not threaded in those cases. It's possible that it is a model or year change but at this point I haven't seen a single picture that indicate that the roof rail attachment points are threaded. Can you tell us what year/location/model you have seen where the sleeve is threaded. Or maybe no sleeve but a welded nut...?
 

dharmasprint

Active member
I have a 2011 Ncv3. There were a series of plastic plugs in the roof rail mount holes that were painted over at the factory. Upon investigation, I found that nothing was threaded. In order to secure my Unistrut rails, I installed plus nuts in the holes using the three forward holes for the front section and the three rear holes for the back section. There are two sections for few reasons. One is that the fantastic fan is mounted mid roof. Another is that the roof rail slots are curved, so a 10' length of Unistrut is not going to sit in the slot. The solar panels are mounted to front rails with a slight cantilever, forward of the fan.

To seal everything, I used urethane body adhesive between the unistrut and the body, then applied dicor sealant to every washer and bolt assembly. So far so good. I plan on putting a air deflector on the front of the solar panel mount because in high head winds, the uplift causes the unistrut to creak.
 

Eric Experience

Well-known member
Bora
I am in Australia and my vehicles are all Rest Of The World specks, If you are in the states you will have the Nafta cheap as possible spec vehicles. Eric.
 

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